Tennis racket



May 10, 1927.

C. SCHINDLER TENNIS RACKET Filed' Feb. 10, 1926- ATTORNEYS.

Patented May 10, 1927.

UNITED STAT P A TENT 0 FT lC E cantfsontnntnnror streamers, nas acrnrsnmrs, assieno'n, B'Y DIRECT Ann avrn'snn ASSIGNMENTS, T0 CARL *scninntnn, Inc, AE'CORPORATION or Minestrone- TEN-ms Application fired February This invent-ion rel-atesfto rackets or bats such as are in common use today forplaying such games as lawn tennis, badminto'miand the like. Such rackets or bats are formed of a frame forming the head of the racket, across and lengthwise of which are tightly stretched stringsbr cords of gut, silk or the like, to form a network, filling the frame. The frame or head is connected to a handle at one end. My invention is particularly addressed to a means and method of stringing such a racket or bat, whereby no string will be fixed, either positively or frictionally, at any point between its ends, to the end that the elasticity and resiliency of the enti-re string may be availedof in response'to any strain ,put upon it, either by the impact of a ball or by the stressesengendered by variations in v atmospheric moisture or heat. The advantages of this method are important. A string held at points between its ends becomes in effect several shorter strings, set end to end, with whatever advantages and disadvantages follow from this fact.

In the drawings:

Figures 1 and 2 are front and edge views respectively of the ordinary racket, on a reduced'scale; V I

Figure 3 is an inside view of a portion of the rim of my racket;

Figure 4: is an outside view of a portion 'ofthe rim of my racket; I I

Figure 5 is aplan view of a portion of the outside of the rim showing the abutment inplace;

Figure 6 is a cross-sectional view, indicating the slant of a pair of apertures, transversely of the rim; 7 v

Figure 7 is a sectional view, indicating the slant of a pair of apertures, longitudinally of the rim;

Figure 8 is a plan view showinga string rounding; the abutment and indicating the slant of the a, and, 6, holes; j

Figure 9 is a sectionon line 99,of F igure 8, also indicating the slant of the. a, and, b holes. I I

Inthe standard racket, the head is inade up of an oval frame A of wood, 110 one end of which is secured a handle B, The frame oftheh'ead A is t a'rerced atfregular intervals, with small holes, a, 21-, passing from the in- I 'side surface of the rmmetbthe outside Sim nAoKn'r.

1c, 1926. Serial No. seats.

race. The net, which fills in and is ,carried by the frame is made up oflengths of string 1), usually of .gut, crossing from one side of the frame to the other, parallel to all other cross-strings, and'o'f string E from one end of the frame to the other, parallel to all other lengthwise strings, the lengthwise strings crossing and being crossed by, all cross-strings, alternately above and beneath.

In practice, two strings are usually employed instringing a racket, one, for the crosswise stringsand the other, E, for the lengthwise stringing. Beginning with the cross string (for example) one end is passed through a hole in the frame adjacent to one end of the frame and across the head and through an opposite hole in the opposite side of the head to the outer surface of the frame. Here it is bent at an angle of ap- .pI'OXlIHItGlY .90 and carried to the next 'hole in the direction of the other end of the frame from that where the start is made. Here the string is again bent at an angle of approximately 90 and repassedthrough a hole in the side of the frame across the 'frame where the process is re peated, the string being woven back and forth across the head through the frame holes, making two bends of approximately 90 each at each reversal of direction.

The operation of stringing, if the above were all, is very simple, but the requirements of a good racket require that each stretch of string shall be under tension.(say about forty pounds) and that the several stretches shall be substantially uniform in tension. This is necessary in order that a resilient net may be formed. If the strings are not under tension or not under sufficient tension, the net is slack and dead. If the several stretches are under irregular tension the net will not be true and the motion of the. ball will become incalculable, that is, the player will be unable to place the ball, be he ever so skilful. It is obvious therefore that tension is necessar to resiliency and that even tension is necessary to produce a reliablejplaying instruinent for-the adept.

, The or my inventien is to give a net increased resiliency and to provide means wh'erebiythe tension of the several reaches of string ,f-r'oln rim to riin may gautomatically adjust themselves to a perfect banshee of tension.

It is obvious that to attain and retain any given tension it is necessary that there be fixed abutments, for if the abutments yield or spread the tension may be varied to destruction. Such abut-ments are found in the standard racket in the opposed rims of the head, but these, by the present stringing method not only require that each reach of stringing be separately tensi-oned as nearly as may be in accord with all other reaches, but be entirely dependent upon itself for resiliency. This arises from the fact that the string in its passage through a rim is bent twice 90 giving such frictional engagement with the rim as to practically cut off each reach from adjacent reaches, the net thus being in effect formed of a multiplicity of short sections of string frictionally anchored at each end to a fixed abutment. Short sections are obviously less resilient than longer sections and sharp bends as anchorages obviously invite breaks at the bendswhere in fact ninety per cent of all breaks occur.

My improvement obviates these difficulties in a simple and effective manner. The tensioning of each reach of stringing is effected between fixed abutments hard and unyielding, but thereafter the several reaches are thrown together to form in effect one long string of substantially uniform tension from end to end, the several reaches giving and taking to attain this uniformity. Furthermore, the effect of the impact of a ball upon any one reach is not confined to that one reach but is transmitted to adjacent reaches so that the strength and resiliency of more than one reach is invoked and this is accomplished by eliminating angular bends in the string and thus eliminating the frictional, the wearing and the weak spots in the stringing, and eliniiinating also a large proportion of the breaks.

My improvement has made possible the satisfactory substitution of silk strings for the gut strings formerly and still used. Gut of good quality, i. e. smooth membrane, is getting scarce and costly and the rough membrane is not only rough but uneven and full of weak spots, so that strings formed thereof are inferior to silk. Silk strings excel the best gut in evenness of diameter, in freedom from flaws, and in tensile strength. They are slightly inferior to the best gut in resiliency, but, by my new invention, silk strings become in the matter of resiliency, equal or superior to gut.

My improved racket is made up, as usual, of the oval-rim head, having a handle at one end, strung, as is customary, cross-wise and lengthwise. In the regular racket, the apertures are bored perpendicularly from one side to the other of the rim, around the rim, sometimes in a straight line, inside and outside of the rim, and sometimes the outer end of the holes is a little above or below the medial longitudinal centre of the rim (see Fig. 2). The string is brought through one hole, from the inside to the outside of the rim, tensioned, temporarily held with a blunt awl and bent along the outside of the rim to the next hole, where the string is bent and passed in again through the hole, and so on, the sections of the string along the outside of the rim being approximately at right angles to the direction of the string across the head and lying in a broken line along the outside of the rim.

In my improved racket I preferably provide holes through the rim which pass slant-- ing from the median longitudinal line of the inside of the rim, at an angle running in the direction in which the string is being woven, i. e. to a point a little to one side or the other of the median line of the out side of the rim, and which pass on .repassing the string inward through the rim, from a point a little to one side of the median line of the outside of the rim, slanting forward to the median line of the inside of the rim (see Fig. i, a, b; Figs. 6, 7, 8 and 9). In other words, the direction of the string holes has two components, one transverse of the rim and the other longitudinal of the rim.

Around the outer side of the rim, along the median longitudinal line, I arrange a cylindrical abutment, preferably of polished aluminum rod, say one-eighth inch diameter. It will be apparent that the stringing holes will be arranged alternately to one side or the other of the line of contact between the abutment and the outside of the rim, that an, a, hole for example slanting from the inside of the rim, forward to one side of the outside median line and in the direction in which the stringing is proceeding, is related to a hole, 6, slanting from the opposite side of the outside median line, in the direct-ion in which the stringing is proceeding, to the median inside line of the rim, and that the string, coming to the inside of the rim at an, a, hole. substantially perpendicular to the rim, will make a mi nute angle and pass through the, a, hole to the outside of the rim, then over and along the polished cylinder and into the, 6, hole to the inside of the rim, which it will leave at a minute angle, substantially perpendicular thereto. This will be repeated at each crossing of the string from rim to rim, The pressure upon the polished cylinder will. be transmitted to the entire periphery of the rim, instead of, as at present, that part of the rim between every other pair of holes, i. e. substantially only about one half the periphery of the rim (see Fig. 2).

The course of a string'from the inlet of an, a, hole to the exit from a, 6, hole, is as follows (see Figs. 8 and 9). Entering the rim at the, a, hole a slight angle, compound transverse and longitudinal of the rim, in the direction in which the stringing is proceeding, carries the string toa point slight-1y under and to one side of the contact line of the abutment W. Here it is forced outward by the abutment and slants, at a slight angle forward around the abutment to the 1) hole, where the abutment holds it to one side of the entrance to the, 6, hole, with it enters, with a slight angular change of direction and passes to the exit on the inside of the rim which it leaves, by a slight angular change of direction, substantially perpendicular to the plane of the inner face of the mm.

In this passage into, twice through and then out of the rim, the string reverses its direction, through 180, but in the process passes no angular surfaces of greater than and only four of these changes or angles, 140 being achieved in rounding the abutment. The deflection of the string, to one side, where it takes and leaves the abutment, by the positioning of the outer rim openings partly beneath the abutment has a marked effect in negativing frictional contact of the string with the edge of the opening as the string leaves the, a, hole and as the string enters the, Z), hole.

The efi'ect of this method of stringing is as if the string at the rim passed over a pulley, so that to any sudden strain imparted to any cross or lengthwise reach of string, the string may render over the abutments at each end and transmit a part of the strain in both directions to adjacent reaches of string. The result is a great increase in the resiliency of the net and also that the playing surface of a racket is greatly extended toward the rims, without loss of resiliency, whereas in the racket as heretofore strung the playing surface was practically limited to at or near the center of the net and was boardy or hard and lifeless at or toward the rim. The life of the racket has also been practically altered so that nothing but a breaking of the rim by accident can destroy the usefulness of the racket. In the old style method of stringing, broken strings were frequent, usually at the bends, and the cutting effect of the taut strings upon the edges of the holes was such that two or three restriiigings'was as much as could be had. With my new racket there are few breaks of the string at the rim and when restringing becomes necessary, it may be done as often as desired since the abutment supports practically the entire wear of the string.

Another advantage of my new racket over the old style, is the fact that the abutment spreads the strain of the taut strings over the entire perimeter of the head, instead of concentrating it at those parts of the rim engaged by the string in passing from one hole to the next, alternate portions of the rim supporting nothing.

The upper surface of the operative rim,

in my device, is on the plane of the contact surface of the abutment. For finish, or to give protection to the abutment and string, sides, (l, may be formed (see Fig. 9).

I claim:

1. In a racket, comprising a handle and a head, having side and end rims; a multiplicity of pairs of apertures through the rim from the inside to the outside of the rim one aperture of each pair slanting from the inside in the direction of stringing and the other from the outside in the direction of stringing; an unyielding hard abutment laid along the outerside of the rim; strings crossing the head back and forth from rim to rim, through the rim apertures and around the abutment.

2. In a racket, comprising a handle and a head, having side and end rims; a multiplicity of pairs of apertures through the rim from one side to the other of the rim, one aperture of each pair slanting transversely from the inside to one side of the median plane of the head on the outer side and also longitudinally in the direction of stringing and the other aperture slanting transversely from the other side of the median line on the outer side of the rim and also longitudinally in the direction of stringing, to the median line on the inner side of the head; an unyielding hard abutment laid along the outerside of the rim; strings crossing the head back and forth from rim to opposed rim, through the pairs of rim apertures and around the abutment.

Signed at Boston, Massachusetts, this twenty-ninth day of January, 1926.

CARL SCHINDLER. 

